Frequent Rubber Eggs and One Hen Recently Died...

My partner and I tend a small flock of chickens. We originally had 8 in total, one rooster and 7 hens, but have lost two over the course of a year. They are all one year old and we got them from a large hatchery in ohio. We had a barred rock, a dominique, a cream legbar, a lavender orpington, a buff chantecler, a buff orpington, and an astralorp. Our dominique either ate something that got lodged deep in her gizzard and was unretrievable or had an inborn genetic problem. At about 9 months, she started wasting away and was very sick and fragile by the end. Our vet couldn't help. We gave her antibiotics which did not help and that is all she said she could do. This weekend, we lost our buff orpington. She was fine in the morning, healthy looking and fully active, no signs of pain or anything a miss, but when I went out to put them away at night, I found her dead in the nesting box, where it looked like she had simply ran to and collapsed. When I inspected her, she appeared to have had a prolapsed intenstine or uterus. There was blood around her vent and shiny pink flesh protruding. We hadn't noticed this at all that morning. She had been a good layer, regularly laying large brown eggs, but not so large that I would have immediately suspected a potential problem (no double yolks either). She was healthy and active in every other way. They have a 3/4 acre pen to run and frolic in all day, and we feed them greens from around the yard that we know are safe. They have regular feed with separate containers for oyster shell and grit. We change their water daily and add apple cider vinegar sometimes. We don't do treats hardly ever. The hens aren't overweight at all, or underweight. They're just right.

Ever since she started laying, Buff would periodically lay a rubber egg. We would find it on the floor of the coop. She did this about once a week consistently. Sometimes two a week. The chickens are in a protected and low stress area. I'm worried the rubber eggs may have been a symptom of her sudden death to come, but I need a third party opinion. Should the rubber egg laying have told me she would likely have potential problems? I'm sad about her death, but I'm also asking for the health of the rest of my flock. My cream legbar is also a good layer, but gives me a rubber egg about once a week as well. Should I be worried about her?